Abstract: An image forming unit forms test images of a color of the same type as a first color using toner of a second color and toner of a third color, transfers first and second test images, fixes the test images on a sheet, controls a sensor to read the test images, determines sampling timings for the test images based on an output signal related to the first test image outputted from the sensor using a color filter of a fourth color, acquires a result of reading the test images based on a reading result of the test images on the sheet by the color sensor using a color filter of the first color and the sampling timing, and determines a transfer voltage based on the result of reading the test images.

Abstract: An image forming unit forms test images of a color of the same type as a first color using toner of a second color and toner of a third color, transfers a first and second test images, fixes the test images on a sheet, controls a sensor to read test images, determines sampling timings for the test images based on an output signal related to the first test image outputted from the sensor using a color filter of a fourth color, acquires a result of reading the test images based on a reading result of the test images on the sheet by the color sensor using a color filter of the first color, and the sampling timing, and determines a transfer voltage based on the result of reading the test images.

Abstract: With stoppage of recording material feeding including a first belt and a second belt (YES in S1), a controller causes cooling operation for the recording material by a cooling fan and a belt fan to continue without stop (S4). By continuing the cooling operation of a recording material cooling device, even if the recording material stagnates in the recording material cooling device in a state of being nipped by the first belt and the second belt, the temperature of the recording material can be lowered. Then, the toner on the recording material is cooled, the toner on the recording material is unlikely to adhere to the first belt or to the second belt.

Abstract: With stoppage of recording material feeding including a first belt and a second belt (YES in S1), a controller causes cooling operation for the recording material by a cooling fan and a belt fan to continue without stop (S4). By continuing the cooling operation of a recording material cooling device, even if the recording material stagnates in the recording material cooling device in a state of being nipped by the first belt and the second belt, the temperature of the recording material can be lowered. Then, the toner on the recording material is cooled, the toner on the recording material is unlikely to adhere to the first belt or to the second belt.